Recently, electronics devices, particularly, devices associated with information have been increasingly produced in the society which is changing to a mass production and mass disposal society. Examples of main components of the electronics devices encompass a semiconductor, a flat display panel such as a liquid crystal panel, a solar battery, a semiconductor device, and a memory.
The electronics devices are produced by use of a vacuum film forming device which employs a vacuum film forming method such as a sputtering method, a vacuum vapor deposition method, or an ion plating method. A film forming material of rare metal is frequently used.
Further, recently, flat panel displays have been in widespread use for various commodities and in fields. Therefore, further increase in size, high-definition, and low power consumption of the flat panel displays have been required.
Under the circumstances, an organic EL display device including organic EL elements which utilize electroluminescence (hereinafter referred to as “EL”) of an organic material has gained great attention. This is because the organic EL display device is a solid-state flat panel display having advantages such as low voltage driving, high-speed response, and self-luminescence.
The organic EL display device is configured, for example, so that organic EL elements are connected to respective TFTs (thin film transistors) on a substrate such as a glass substrate.
Each of the organic EL elements is a light emitting element which can emit high luminance light by being driven by a low-voltage direct current. The organic EL elements have a layer stack structure in which respective first electrodes, an organic EL layer, and a second electrode are stacked in this order. The first electrodes are connected to the respective TFTs.
The organic EL layer provided between the first electrodes and the second electrode is an organic layer in which layers, such as a hole injecting layer, a hole transporting layer, an electron blocking layer, a luminescent layer, a hole blocking layer, an electron transporting layer, and an electron injecting layer, are stacked.
A full-color organic EL display device is generally configured so that red (R) organic EL elements, green (G) organic EL elements, and blue (B) organic EL elements, which serve as respective sub-pixels, are arranged on a substrate. The full-color organic EL display device displays an image by causing, by use of TFTs, the red (R) organic EL elements, the green (G) organic EL elements, and the blue (B) organic EL elements to selectively emit light having a desired luminance.
The organic EL elements of a light emitting section of the full-color organic EL display device are generally formed by carrying out vapor deposition of organic films. During production of the full-color organic EL display device, luminescent layers made from respective organic light emitting materials that emit red light, green light, and blue light, respectively, are formed in a predetermined pattern for the respective organic EL elements that are the light emitting elements.
A film having the predetermined pattern can be formed by means of vapor deposition, for example, by a vacuum vapor deposition method which employs a mask called “shadow mask” for vapor deposition, an inkjet method, or a laser transfer method.
Among the methods, the vacuum vapor deposition method is most popularly employed these days.
According to the vacuum vapor deposition method, vapor deposition of a vapor deposition material is carried out on a film formation substrate on which a film is to be formed, by heating and subliming the vapor deposition material in a high vacuum by use of a vapor deposition source (i) in which the vapor deposition material is to be put and (ii) which is called “crucible” or “boat”.
Specifically, a film having a desired pattern can be formed by carrying out, via openings formed in the mask, vapor deposition of the vapor deposition material which has been outputted as vapor deposition particles from the vapor deposition source, in a vacuum chamber of a vacuum vapor deposition device.
Thus, the organic EL elements of the light emitting section of the full-color organic EL display device are formed by the vapor deposition of the organic films.
According to the vacuum vapor deposition method, as early described, the vapor deposition particles obtained by heating and subliming the vapor deposition material are outputted from the vapor deposition source. Therefore, scattered vapor deposition particles attach to components other than the film formation substrate such as a TFT substrate.
The vacuum chamber of the vacuum vapor deposition device includes the components such as a vapor deposition-proof plate and a shutter.
The vapor deposition material which has attached to the components, that is, the vapor deposition particles which have attached to the film formation substrate such as the TFT substrate are waste unless the vapor deposition particles are collected, though an organic material for the organic films is expensive.
Actually, it is impossible to recycle an organic material which has attached to a vapor deposition-proof plate and other components in a vacuum chamber of an apparatus that is used for producing large numbers of organic EL display devices. Therefore, a material utilization rate is low.
What is meant by the material utilization rate is how much a vapor deposition material is actually used to form organic films.
The material utilization rate is increased by collecting and recycling the vapor deposition material which has attached to the components other than the film formation substrate.
As a method for increasing the material utilization rate, for example, Patent Literature 1 discloses a method for collecting a vapor deposition material which has attached to a cell shutter by (i) heating and vaporizing the vapor deposition material and (ii) cooling the resultant vapor in a shroud in which a coolant is circulated.
Patent Literature 2 discloses a method for collecting a vapor deposition material which has attached to a shutter plate by (i) melting the vapor deposition material by use of a heater included in a shutter and (ii) causing the resultant molten to drop into a vapor deposition source.
Patent Literature 3 discloses a method for collecting, in a crucible, a vapor deposition material which has attached to a lower surface of a cell shutter by heating the cell shutter by use of a heater so that the vapor deposition material is vaporized.
Patent Literature 4 discloses a method for collecting a vapor deposition material which has accumulated on a blocking wall which is included in a vapor deposition material collector that has a vapor exhaust port. The vapor deposition material collector is provided so as to cover a vapor exit. The method is carried out with respect to the vapor deposition material collector which has been taken out after vapor deposition. The vapor deposition is carried out while a scattering angle of a vapor flow from a vapor deposition source toward a substrate to be processed is being controlled.
Patent Literature 5 discloses that (i) members such as a shutter in a chamber, on which members an organic material is to be accumulated, are made from an inert material which does not denaturalize the organic material and (ii) the organic material which has accumulated on the members is collected.
Patent Literature 6 discloses a method for collecting a material which has attached to a film forming jig by injecting water to the material by use of a water jet.